JP2025030765A - How to construct beams for floor expansion - Google Patents

Abstract

To provide a beam construction method for floor extension which has excellent workability by smoothly positioning and joining a new beam at an installation position of an existing member, while eliminating lifting of the new beam by an operator and enhancing work safety, in constructing a beam for floor extension at an open ceiling of an existing building.SOLUTION: A beam construction method for floor extension for constructing beams B1, B2 for floor extension with respect to an open ceiling of an existing building includes a new beam construction step of, out of a girder B1 and a beam B2 which are a plurality of new steel beams crossing each other, with respect to a floor extension area ZA with respect to the open ceiling, both end parts of the girder B1 are joined to existing steel members G3, G4 of the existing building, one end of the beam B2 is joined to the girder B1, and the other end is joined to existing members G1, G2. In the new beam construction step, at two points of the existing members G1, G2, a rope R is directly or indirectly mounted, and by a lifting instrument W mounted on the rope R, the new beam B1 is lifted and joined to the existing members G3, G4.SELECTED DRAWING: Figure 5

Description

The present invention relates to a method for constructing beams for floor expansion.

In existing buildings with an atrium, renovations are sometimes carried out to add floor space to the atrium, for example because an additional family will be living together. In such renovations, new steel beams (expansion beams) are constructed in the expanded area of the atrium, and flooring is then installed on the new beams. The construction of these new beams is done in a way that the new steel beams that intersect with each other are joined to the existing steel members (existing beams, etc.) of the existing building.

The commonly used method for joining a new steel beam to an existing steel member is, for example, to have a worker stand on a stepladder installed on the first floor, lift the new beam to the installation position on the existing member, and then join the end of the new beam to the existing member while maintaining this position.

As a result, there is a high risk that the newly constructed beams being held up by workers will fall, posing a major issue with work safety. Furthermore, there is also the issue of workability, as it is difficult for workers to smoothly align the bolt holes of the newly constructed beams with the bolt holes of the existing members when they lift them up.

In view of the above, when constructing floor expansion beams in an atrium of an existing building, there is a need for a method of constructing floor expansion beams that is easy to work with, eliminates the need for workers to lift the newly constructed beams, increases work safety, and allows the new beams to be smoothly aligned to the installation positions of existing components.

Here, Patent Document 1 proposes a method for expanding the floor space of a reinforced concrete structure. This method for expanding the floor space of a reinforced concrete structure involves erecting multiple girders made of lightweight box-shaped steel pipes in parallel between the opposing interior vertical wall surfaces of the void space of the reinforced concrete structure, stretching fire-resistant lightweight materials such as foam concrete panels on the upper and lower surfaces of the girders, covering the upper surface of the upper fire-resistant lightweight material with floor plywood, and covering the lower surface of the lower fire-resistant lightweight material with a ceiling base board to form an expansion space in the void space.

Japanese Patent Application Publication No. 5-25944

The method for expanding floor space of a reinforced concrete structure described in Patent Document 1 is literally a method for expanding floor space of a reinforced concrete structure, and therefore does not propose a construction method for expanding floor space beams that eliminates the need for workers to lift new beams and increases work safety when joining new steel beams to existing steel members in an open void in an existing building, as described above.

The present invention was made in consideration of the above problems, and aims to provide a method for constructing beams for floor expansion in an atrium of an existing building, which eliminates the need for workers to lift the newly installed beams, thereby improving work safety, while allowing the new beams to be smoothly aligned and joined to the installation positions of existing members, resulting in excellent workability.

In order to achieve the above object, one aspect of the method for designing floor expansion beams according to the present invention is to
A method for constructing an expansion beam in an existing building, comprising:
A new beam construction process is provided for connecting both ends of a large beam and a small beam, which are a plurality of mutually intersecting steel-framed newly constructed beams, to existing members of the steel-framed structure of the existing building, connecting one end of the small beam to the large beam, and connecting the other end of the small beam to the existing member, for the expanded area for the atrium.
The new beam construction process is characterized in that a rope is attached directly or indirectly to two points of the existing member, and the new beam is lifted by a lifting device attached to the rope and joined to the existing member.

According to this method, a rope is attached directly or indirectly to two points on the existing member, and the new beam is lifted by a lifting device attached to the rope and joined to the existing member. This eliminates the need for workers to lift the new beam, improving work safety, while also improving workability by allowing the new beam to be smoothly aligned and joined to the installation position of the existing member.

Here, "attaching a rope directly or indirectly to two points on an existing member" includes not only directly attaching both ends of the rope to two existing members, but also indirectly attaching the rope to an existing member by attaching one end of the rope to another member, such as a support, that is attached to the existing member. New beams include main and secondary beams. Existing members include existing beams and existing columns. Furthermore, ropes include steel wires and chains in addition to ropes and cordage.

After the new beam is raised to the installation level by a lifting device attached to a rope, the end of the new beam and the existing member are joined by bolting or welding. Here, by using a one-sided bolt to join from the atrium side, in cases where it is not possible to reach the back side of the existing member, for example when there is a room in use adjacent to the existing member, it is preferable to insert the bolt from the atrium side into a bolt hole already opened in the existing member or a new bolt hole opened from the atrium side, so that construction does not affect the room, etc.

In addition, another aspect of the method for constructing floor extension beams according to the present invention is as follows:
A tensioner is disposed at a midpoint of the rope, and tensions the rope using the tensioner.

According to this embodiment, the rope is tensioned by a tensioner located midway along the rope, which is preferable because it allows the newly constructed beam to be lifted in a stable position.

In addition, another aspect of the method for constructing floor extension beams according to the present invention is as follows:
Attaching a support directly or indirectly to the existing member;
The method is characterized in that the rope is attached to the support and the lifting device attached to the rope is positioned at a position higher than the installation level of the new beam to be joined to the existing member.

According to this aspect, a rope is attached to a support that is directly or indirectly attached to the existing member, and a lifting device attached to the rope is positioned at a position higher than the installation level of the new beam to be joined to the existing member, so that the new beam can be lifted to the installation level of the new beam and joined to the existing member.

Here, "the support is directly or indirectly attached to the existing member" includes not only the support being directly attached to the existing member, but also the support being indirectly attached to the existing member by fixing the support to another member, such as a support fixing jig, that is attached to the existing member.

In addition, another aspect of the method for constructing floor extension beams according to the present invention is as follows:
The method is characterized in that a support pillar fixing jig is attached to the existing member, and the support pillar is attached to the support pillar fixing jig.

According to this aspect, by attaching a support to which the end of a rope is attached to a support fixing jig that is attached to an existing member, the ease of installation is improved when installing a rope to which a hoisting device for suspending a new beam is attached at a level higher than the installation level of the new beam. For example, when a support is directly attached to an existing member, the length of the support increases and the weight increases, which may reduce the ease of attaching the support to the existing member and the ease of handling the support, but this problem is solved by the method of attaching the support to the support fixing jig.

In addition, another aspect of the method for constructing floor extension beams according to the present invention is as follows:
The rope is attached to the two pillars, the lifting device is attached to the rope, and the two pillars are attached to the corresponding pillar fixing jigs simultaneously or sequentially.

According to this method, after attaching both ends of the rope to which the lifting device and tensioning device are attached to two supports, two workers can simultaneously attach the two supports to the corresponding support fixing jigs, or one worker can attach them sequentially, so that both ends of the rope to which the lifting device is attached can be efficiently attached to two points on the existing member.

In another aspect of the method for constructing floor extension beams according to the present invention,
The two points are points where a straight line passing through the longitudinal center or its vicinity of the newly constructed beam to be lifted intersects with the existing building, and the lifting device is installed at or near the center.

According to this aspect, the two points at which the ends of the rope are attached to the existing members are the points where a straight line passing through the longitudinal center of the newly constructed beam or its vicinity intersects with the existing building, and by installing a lifting device at or near this center of the rope, the newly constructed beam can be lifted stably while suppressing rattling of the lifting device that lifts the newly constructed beam.

In another aspect of the method for constructing floor extension beams according to the present invention,
The attachment of the pillar or the pillar fixing jig to the existing member is characterized by bolting from the open space side using a one-sided bolt.

According to this aspect, the support or support fixing jig is attached to the existing member by bolting from the atrium side with a one-sided bolt, and as described above, the bolt is inserted from the atrium side into a bolt hole that has already been opened in the existing member or a bolt hole newly opened from the atrium side, which is preferable because construction does not affect rooms currently in use.

In existing beams and other existing components, bolt holes for fixing a jig for installing a safety net may be provided at a specified interval when constructing a new existing beam, so the bolt holes already provided in the existing component may be used. If there are no bolt holes in the existing component at the location where you want to install the support fixing jig, you can align the end of the new beam with the installation position of the existing component while hanging the new beam with a lifting device, and use the bolt holes in the new beam as a guide to construct bolt holes in the existing component.

In addition, welding joints require that work be done by qualified personnel, and there are issues with the quality of the work depending on the skill of the worker. Furthermore, there is a risk of the insulation material or wooden base laid inside the existing components catching fire during welding joints. For safety reasons, if welding joints are performed after removing surrounding components such as ceilings and facings, the work area will be wider than necessary, which is undesirable. In contrast, by using a one-sided bolt to perform the bolt joint from the atrium side, the various issues inherent to welding joints mentioned above can be resolved.

As can be understood from the above explanation, the method for constructing beams for floor expansion of the present invention can provide a method for constructing beams for floor expansion in an open void in an existing building, which eliminates the need for workers to lift the newly installed beams, thereby improving work safety, while smoothly aligning and joining the newly installed beams to the installation positions of the existing members, thereby providing an excellent workability.

FIG. 1 is a floor plan of a second floor of an example of an existing building to which the method for constructing floor expansion beams according to an embodiment of the present invention is applied. FIG. 2 is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method according to the embodiment. Following Figure 2, this is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method of the embodiment. Following Figure 3, this is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method of the embodiment. 1 is a diagram illustrating a state in which a lifting device is attached to a rope whose both ends are attached to two supports. FIG. Following Figure 4, this is an explanatory diagram illustrating the new beam construction process of the floor expansion beam construction method of the embodiment.

Below, an example of a floor expansion beam construction method according to an embodiment will be described with reference to the attached drawings. Note that in this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant explanation.

[Method of constructing beams for floor expansion according to the embodiment]
An example of the method for constructing beams for floor extension according to the embodiment will be described with reference to Fig. 1 to Fig. 6. Fig. 1 is a floor plan of the second floor of an example of an existing building to which the method for constructing beams for floor extension according to the embodiment is applied. Figs. 2 to 4 and Fig. 6 are explanatory diagrams for explaining the new beam construction process of the method for constructing beams for floor extension according to the embodiment, respectively, and Fig. 5 is a diagram for explaining a state in which a lifting device is attached to a rope whose both ends are attached to two pillars.

The following describes an example of an existing building to which the floor expansion beam construction method according to the embodiment can be applied, using a steel-framed, multi-story detached house with an open ceiling.

The second floor of the building to be constructed, shown in Figure 1, is equipped with stairs and free space around the atrium. In the illustrated example, the atrium is provided above the porch, entrance, and living room on the first floor (all of which are shown in parentheses as they are on the first floor). On the second floor, surrounding the atrium, there is an existing beam G1 on the outdoor side between the first and second floors, an existing beam G2 on the indoor side facing the existing beam G1, and another pair of existing beams G3 and G4 perpendicular to these.

As shown in FIG. 2, the rectangular area in plan view surrounded by the four existing beams G1 to G4 is set as the expansion area ZA. In this expansion area ZA, multiple new steel beams that intersect with each other are erected in sequence according to the burden area of the expansion area ZA.

Specifically, as shown in Figure 3, a beam assembly BU consisting of two new intersecting beams B1 and B2 will be constructed as a beam assembly BU capable of supporting the floor load of the entire area of the expanded area ZA.

In the illustrated example, of the two new beams B1 and B2, the other new beam B1 (winning beam) to which the end of the other new beam B2 will be attached becomes the main beam, and the new beam B2 (losing beam) to which one end is attached becomes the minor beam. During construction, the main beam B1 is constructed first in the expansion area ZA, and then the set BU is constructed in the order of constructing the two minor beams B2.

To explain the method for constructing beams for floor expansion in detail, first, the main beam B1 is placed on the floor surface of the first floor in a position where it can be lifted, as shown in Figure 4.

Now, referring to Figure 5, we will explain an example of equipment for lifting the main girder B1 and attaching it to the existing beams G1 and G2. The equipment in the illustrated example is also used to lift the secondary beam B2, which is then attached to the existing beams G3 and G4 and the main girder B1.

Workers attach support fixing jigs J to the opposing existing beams G1 and G2, for example using a stepladder installed on the first floor.

The support pillar fixing jig J is formed by welding a single pipe C1, for example, φ48.6 mm, to a steel fixing plate E. The fixing plate E has a bolt hole H2.

The worker aligns the bolt hole H2 of the fixing plate E with the bolt hole H1 that has already been drilled in the existing beams G1 and G2, and attaches the support pillar fixing jig J to the main girder B1 by inserting the one-sided bolt SB in the X1 direction from the atrium side. If the bolt hole H1 does not exist in the existing beams G1 and G2 at the position where the support pillar fixing jig J is to be attached, the bolt hole H1 may be drilled at the desired position from the atrium side.

The pillar fixing jig can take various forms in addition to the illustrated example. For example, a steel plate that is inserted into the inside of a pillar made of a single pipe is connected to a steel fixing plate, or a single pipe clamp that holds the pillar is connected to a steel fixing plate.

The one-sided bolt SB used can take a variety of forms, but the form shown in the figure has a roll plate that can rotate freely around the rotation axis at the tip, and is inserted into the bolt holes H2 and H1 that communicate from the atrium side. When the roll plate protrudes from the bolt hole H2 to the outside of the girders G1 and G2, the roll plate rotates around the rotation axis, forming an L shape as a whole, and the roll plate engages with the girders G1 and G2.

Although not shown in the figures, other types of one-sided bolts include those equipped with a washer and a leg-spreading member, which is inserted into the bolt holes of multiple joined members, and then the bolt is tightened so that the leg-spreading member opens to the side and approaches the washer, joining multiple joined members using the washer and the open leg-spreading member. Yet another type is one in which a bolt is screwed into the bolt holes of multiple joined members to join multiple joined members.

In this way, the support fixing jig J is attached to the existing beams G1 and G2 by bolting from the atrium side with one-sided bolts SB, and the bolts are inserted into the bolt holes H1 of the existing beams G1 and G2 from the atrium side, which is preferable as it prevents construction work from affecting rooms currently in use.

For example, Figure 4 shows the pillar fixing jig attachment positions P1 and P2 where a pair of pillar fixing jigs J are attached to existing beams G1 and G2.

The position P1 where the support fixing jig is attached is a position where it is not possible to reach the back side of the existing beam G1 (joining from the back side is not possible), so construction is possible by bolting from the open space side using a one-sided bolt SB.

On the other hand, the pillar fixing jig installation position P2 is located behind the existing beam G2, and since there is free space available for use by residents behind the existing beam G2, workers cannot reach behind the existing beam G2 either, so construction can be performed by bolting from the open space side using a one-sided bolt SB.

On the first floor floor, fasteners F on both ends of a rope R are hooked to hooks Ca at the tops of a pair of pillars C2, and an electric winch W (an example of a lifting device) is attached to the rope R. For example, two workers simultaneously lift each pillar C2 and stand on a stepladder to insert the lower end of the pillar C2 into the single pipe C1 of the pillar fixing jig J in the X2 direction, so that the rope R to which the electric winch W is attached is stretched between two points (P1, P2) of the opposing existing beams G1, G2 via the pair of pillar fixing jigs J and the pillars C2. Here, a method in which one worker sequentially attaches the corresponding pillars C2 to each pillar fixing jig J may also be used.

The support pillar C2 is formed, for example, from a φ42.7 single pipe, and is firmly fixed without rattling when inserted into the φ48.6 mm single pipe C1 as described above. In addition, a stopper ST made of a pin, rebar, a relatively large diameter short single pipe, etc. is attached to the bottom of the support pillar C2, and when the bottom of the support pillar C2 is inserted into a position where it is stable in terms of strength against the single pipe C1, the insertion of the support pillar C2 is stopped by the stopper ST.

The attachment position of the electric winch W to the rope R is set to the center position of the rope R (a position at a distance t from the pair of supports C2), and it is advisable to take measures to prevent the electric winch W from shifting from this center position (not shown).

A tensioner T is provided midway along the rope R (near the fastener F on the right side in the illustrated example), and when the electric winch W is used to lift the girder B1, the tensioner T tensions the rope R and stretches it around a pair of supports C2. For example, the rope R extending from the tensioner T can be hung down to a height within reach of a worker on the first floor, and the worker can tension the rope R by pulling on it.

In FIG. 5, the dashed line connecting the opposing existing beams G1 and G2 represents the girder B1 that is spanned between the existing beams G1 and G2. Since the girder B1 is spanned between the existing beams G1 and G2, the electric winch W that lifts the girder B1 needs to be positioned at a higher level than the installation level of the girder B1.

As shown in the example, by attaching the support C2 to which the end of the rope R is attached to the support fixing jig J attached to the existing beams G1, G2, the rope R to which the electric winch W is attached can be easily installed at a level higher than the installation level of the main girder B1. For example, the support may be directly attached to the existing beams G1, G2, but the length of the support may be longer than necessary, and in that case, the weight of the support may also be heavy, which may reduce the ease of attaching the support to the existing beams G1, G2 and the ease of handling the support.

In contrast, by attaching the pillar fixing jigs J to the existing beams G1 and G2 and attaching the pillars C2 to each pillar fixing jig J as in the illustrated example, the pillars C2 are prevented from becoming excessively long, improving the ease of installation and handling of the pillars C2.

As shown in Figure 4, the mounting positions P1 and P2 of a pair of support fixing jigs are the intersections of a straight line L1 (a virtual straight line) passing through the center O1 of the main girder B1, which is placed in a position where it can be lifted directly above the first floor, and the opposing existing beams G1 and G2. Such support fixing jig mounting positions P1 and P2 can be set in various ways, but as described above, they may be set at a location where a bolt hole H1 has been opened in advance, or at a location where the workability during lifting construction is good. In the latter case, if the bolt hole H1 does not exist in the existing beams G1 and G2, the bolt hole H1 can be opened.

The rope R tensioned by the tensioner T will be positioned directly on the straight line L1 shown in Figure 4.

By lifting the center O1 of the girder B1 placed on the first floor with an electric winch W attached to the center of a rope R stretched between a pair of supports C2, the girder B1 can be lifted to the installation level in a stable posture while suppressing the lateral swaying of the girder B1, and both ends of the girder B1 can be smoothly aligned to the installation positions of the existing beams G3 and G4.

With the girder B1 suspended by the electric winch W, a worker standing, for example on a stepladder, joins both ends of the girder B1 to a pair of existing beams G3, G4 by bolting or welding using bolts or one-sided bolts (joints D3, D4 in Figure 3).

Here, even when connecting the main girder B1 to the existing beams G3 and G4, if workers are unable to reach behind the existing beams G3 and G4 or if it is considered not possible to use a welded connection due to issues with the welded connection, a bolt connection using a one-sided bolt from the atrium side is applied.

Next, as shown in Figure 6, the same method as for lifting the girder B1 and joining it to the existing beams G3 and G4 is applied to lifting the two minor beams B2 and joining each minor beam B2 to the existing beam G2 and the main beam B1, and to joining the existing beam G1 to the main beam B1.

For the upper minor beam B2 in Figure 6, the pillar fixing jig J used when lifting the main beam B1 is replaced and installed at the pillar fixing jig attachment positions P3 and P4 where the straight line L2 passing through the center O2 of the minor beam B2 placed on the first floor floor surface intersects with the existing beams G3 and G4.

Then, the support pillars C2, to which both ends of the rope R to which the electric winch W is attached, used to lift the main girder B1, are rearranged and attached to a pair of support fixing jigs J, and the secondary beam B2 is lifted to the installation level by the electric winch W, and both ends are joined to the main girder B1 and the existing beam G2.

Next, for the lower small beam B2 in Figure 6, the support fixing jig J used when lifting the previously installed small beam B2 is replaced and installed at the support fixing jig attachment positions P5 and P6 where the straight line L3 passing through the center O3 of the small beam B2 placed on the first floor surface intersects with the existing beams G3 and G4.

Then, the pillars C2 to which both ends of the rope R to which the electric winch W is attached, which was used to lift the previously installed minor beam B2, are rearranged and attached to a pair of pillar fixing jigs J, and the minor beam B2 is lifted to the installation level with the electric winch W, and both ends are joined to the main beam B1 and the existing beam G1, thereby constructing the beam assembly BU consisting of the main beam B1 and minor beam B2 in the expansion area ZA (this concludes the new beam construction process).

According to the illustrated method of constructing beams for floor expansion, a rope R is directly or indirectly attached to two points of the existing members G1 to G4, and the new beams B1, B2 are lifted by a lifting device W attached to the rope R and joined to the existing members G1 to G4. This eliminates the need for workers to lift the new beams B1, B2, improving work safety, while also improving workability by allowing the new beams B1, B2 to be smoothly aligned and joined to the installation positions of the existing members G1 to G4.

Note that the configurations described in the above embodiments may be combined with other components, and the present invention is not limited to the configurations shown here. In this regard, changes can be made without departing from the spirit of the present invention, and can be determined appropriately according to the application form.

ZA: Expansion area B1: New beams (main beams, beams for expansion)
B2: Newly installed beam (small beam, beam for floor expansion)
BU: Beams (for floor expansion)
G1: Existing members (existing beams, existing permanent beams, channel steel)
G2: Existing members (existing beams, channel steel)
G3: Existing members (existing beams, channel steel)
G4: Existing members (existing beams, channel steel)
GU: Existing unit beam (existing beam)
D1, D2, D3, D4: Joint R: Rope W: Lifting device (electric winch)
T: Tensioner F: Fastener J: Pillar fixing jig C1: Single tube E: Fixing plate C2: Pillar Ca: Hook H1, H2
N: Nut SB: One-sided bolt P1 to P6: Pillar fixing jig installation position L1, L2, L3: Straight line (imaginary straight line)
O1: Center of main beam O2, O3: Center of sub-beam

Claims (7)

A method for constructing an expansion beam in an existing building, comprising:
A new beam construction process is provided for connecting both ends of a large beam and a small beam, which are a plurality of mutually intersecting steel-framed newly constructed beams, to existing members of the steel-framed structure of the existing building, connecting one end of the small beam to the large beam, and connecting the other end of the small beam to the existing member, for the expanded area for the atrium.
The method for constructing beams for floor expansion is characterized in that, in the new beam construction process, a rope is attached directly or indirectly to two points of the existing member, and the new beam is lifted by a lifting device attached to the rope and joined to the existing member. The method for constructing floor extension beams according to claim 1, characterized in that a tensioner is interposed at a midpoint of the rope, and the rope is tensioned by the tensioner. Attaching a support directly or indirectly to the existing member;
The method for constructing beams for floor expansion described in claim 2, characterized in that the rope is attached to the support and the lifting device attached to the rope is positioned at a position higher than the installation level of the newly constructed beam to be joined to the existing member. The method for constructing beams for floor expansion described in claim 3 is characterized in that a support fixing jig is attached to the existing member, and the support is attached to the support fixing jig. The method for constructing beams for floor extension according to claim 4, characterized in that the rope is attached to the two pillars, the lifting device is attached to the rope, and the two pillars are attached to the corresponding pillar fixing jigs simultaneously or sequentially. The method for constructing beams for floor extension described in claim 1 is characterized in that the two points are points where a straight line passing through the longitudinal center or its vicinity of the new beam to be lifted intersects with the existing building, and the lifting device is installed at or near the center. The method for constructing beams for floor expansion according to claim 3 or 4, characterized in that the support or the support fixing jig is attached to the existing member by bolting from the atrium side with a one-sided bolt.

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